Messages in this thread | | | Date | Sun, 15 Mar 2015 22:04:53 -0700 | Subject | Re: [PATCH v4] x86, kaslr: Access the correct kaslr_enabled variable | From | Yinghai Lu <> |
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On Sun, Mar 15, 2015 at 8:28 PM, Baoquan He <bhe@redhat.com> wrote: > On 03/15/15 at 12:49am, Yinghai Lu wrote: > > It's good to check the ret value as Boris suggested. However it could > fail since early_memremap self fail, e.g slot not found. In this case > making kaslr_enabled true may not be good.
It should not fail. we always follow map/access/unmap. and sometime would have two for copying between them.
> > As Minfei talked with you kaslr_setup_data is a global variable inside > kernel code, it has been ident mapped. Just derefencing the physical > address which is virtual address too and getting the real stored value > may be safer.
No. That ident mapping is set in arch/x86/kernel/head_64.S and it is only for switchover. and it is gone when arch/x86/kernel/head64.c::x86_64_start_kernel/reset_early_page_tables is called.
That reset_early_page_tables will only keep kernel high mapping and clear all other.
Thanks
Yinghai
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